The present invention relates to a twin monopole antenna, and more particularly relates to a twin monopole antenna that is fed by a twin coplanar waveguide and provided for radiating and receiving high-frequency signals in wireless communication systems.
With the advancement of communication technologies, the applications using communication technologies have been increased significantly and the related products have also become more diversified. Especially, consumers have more demands for the functions of communication applications, so that there are many communication applications with different designs and functions continuously appearing in the market. For example, the products with one-piece design of dual-band or triple-band, and the computer network products with wireless communication functions are the main streams in the current market. Moreover, by utilizing IC technologies, the size of products will become smaller in future.
The function of antenna is mainly to radiate and receive signals in communications products, so that the designs and studies of antenna are quite important. In accordance with the demands of operations, there are numerous functions developed for communication products, so that the design of antenna has to be quite diversified, such as a rhombic antenna, a turnstile antenna, an invert-F antenna and a patch antenna, etc., for meeting the requirements various communication products. On the other hand, the properties of antenna are generally known by the parameters of operating frequency, radiation pattern, return loss, and antenna gain, etc.
Among various types of designs, a conventional patch monopole antenna has the attractive features of flatness, simple structure, easy design, etc. Therefore, the conventional patch monopole antenna is very suitable for use in applications in the current communication products. The conventional patch monopole antenna has been utilized popularly in various products and communication systems recently.
However, in common communication systems, the conventional patch monopole antenna cannot provide a better signal-radiating and signal-receiving performance in high frequency, so that the utilization of conventional patch monopole antenna has been limited in the current trend that is gradually moving towards high operation frequency and broader bandwidth.
In the view of the background of the invention described above, an antenna is an important part in wireless communications, since the overall performance of wireless communications is greatly affected by the antenna. Therefore, the features of low cost, high efficiency and simple implementation are the major trends for the design of antenna. Since the conventional patch monopole antenna has several advantageous features, such as flatness, simple structure and easy design, etc., the conventional patch monopole antenna has been popularly used. However, for the conventional patch monopole antenna has the disadvantage of low efficiency in high-frequency operation, the conventional patch monopole antenna cannot be utilized broadly.
Therefore, it is the principal object of the present invention to provide a twin monopole antenna, and more particularly to provide a twin monopole antenna that is fed by a twin coplanar waveguide. The present invention is to attain and provide more complete functions and the range of higher operating frequency by operating the twin monopole antenna of the present invention in different frequency bands, wherein the twin monopole antenna of the present invention has two radiating metal lines, whereby either one of two radiating metal lines can be switched by RF circuit for performing the radiating and receiving operations for the twin monopole antenna in accordance with the environmental signal intensity. Moreover, the implementation of the present invention is valuable in industrial fields, because the twin monopole antenna of the present invention can be printed on a substrate, which makes it easy to be integrated with other associated circuitries.
In accordance with the aforementioned purpose of the present invention, the present invention provides a twin monopole antenna. The twin monopole antenna of the present invention comprises: a substrate having a first surface and a second surface; an upper ground plane that is located on the first surface of the substrate and comprises: a first ground plane, a second ground plane and a third ground plane; a lower ground plane that is located on the second surface of the substrate and comprises: a fourth ground plane; and an inverted-U shaped ground plane having a hollow rectangular surface; a first radiating line located on the first surface of the substrate, wherein a first included angle is located between the first radiating line and the second ground plane; and a second radiating line located on the first surface of the substrate, wherein a second included angle is located between the second radiating line and the second ground plane, and an interval between the first radiating line and the second radiating line.
The main radiating component of the twin monopole antenna of the present invention resides in a structure of two radiating metal lines that are fed and driven by twin coplanar waveguide. According to the design parameters of two radiating metal lines, such as lengths, widths, shapes and included angles, the twin monopole antenna of the present invention can be operated in different frequency bands, and the frequency ratio thereof is also adjusted easily. Moreover, since the radiating metal lines and the ground plane are printed directly on a substrate, the cost is thus lowered and the manufacture can be processed easily.